A high toughness, high strength and high temperature resistant PMI foam

Abstract

The present invention discloses a high-toughness, high-strength and high-temperature-resistant PMI foam, which relates to the field of polymer materials. This PMI foam is prepared by mixing methacrylic acid, methacrylonitrile, initiator, modifier, foaming agent, crosslinking agent and nucleating agent in a specific proportion, followed by mechanical stirring, water bath polymerization and heating foaming. By controlling the polymerization reaction temperature and time and completing it under specific foaming conditions, the obtained PMI foam material exhibits excellent toughness, strength and high-temperature resistance, and is suitable for the field of lightweight and high-strength structural materials.

Description

Technical Field

[0001] The present invention relates to the field of polymer materials, and particularly to a PMI foam with high toughness, high strength and high temperature resistance. Background Art

[0002] With the progress of technology and the continuous improvement of industrial demands, the application demands of high-performance foam materials in fields such as aerospace, automotive, electronics and construction are increasing day by day. However, traditional foam materials have great limitations in terms of strength and toughness, and usually it is difficult to withstand complex and variable external forces, especially in high-temperature or high-impact environments, it is more likely to be damaged. These limitations of traditional foam materials have restricted their applications under many harsh conditions.

[0003] In the aerospace field, during the high-speed flight, takeoff and landing of aircraft and encountering air flow turbulence, the structural components need to withstand huge dynamic loads. PMI (polymethacrylimide) foam has been gradually applied to the sandwich structure, thermal insulation layer and sound insulation material of aircraft due to its excellent light weight and heat insulation performance. However, traditional PMI foam materials still have deficiencies in toughness and strength, and it is difficult to cope with various severe loads during the operation of aircraft. For example, under high-speed flight and strong air flow, the structural components of aircraft need to withstand composite forces such as impact, tension and compression. As one of the supporting structure materials, PMI foam must provide reliable support and buffering to ensure the stability of the aircraft structure and flight safety. Therefore, improving the toughness and strength of PMI foam and enhancing its bearing capacity under complex external forces have become the key directions for improving the performance of aerospace materials.

[0004] In addition, in the automotive industry, the material stability under high-temperature environment is crucial. Traditional foam materials are prone to softening, decomposition and even combustion in high-temperature environments, resulting in performance degradation or material failure, and cannot meet the application requirements of high-temperature parts in the engine compartment. The temperature in the automotive engine compartment can reach up to 100 - 150 °C, and it is required that the material can still maintain excellent heat insulation, sound insulation and structural support performance at high temperatures. Traditional PMI foam materials are prone to degradation at high temperatures and cannot meet the harsh requirements of high-temperature environments. In contrast, PMI foam materials with high toughness, high strength and high temperature resistance show better thermal stability under high-temperature conditions, are not easy to soften or decompose, can remain stable in high-temperature parts such as the engine compartment, and improve the overall reliability and durability of the vehicle.

[0005] In summary, developing a PMI foam material with high toughness, high strength and high temperature resistance has become an important direction for improving the application performance of this material in the aerospace and automotive fields. Summary of the Invention

[0006] To solve the technical problems in the above-mentioned background art, the present invention enhances the strength and toughness of PMI foam materials through modifiers, specific cross-linking and foaming conditions, enabling them to maintain the structural integrity in the face of variable external forces and high-temperature environments, addressing the deficiencies in the prior art and providing a more reliable and safe material selection for applications in the above fields.

[0007] The technical solution adopted by the present invention to solve its technical problems is as follows:

[0008] A high-toughness, high-strength and high-temperature-resistant PMI foam, characterized by comprising the following steps:

[0009] According to mass parts, methacrylic acid, methacrylonitrile, initiator, high-temperature-resistant modifier, foaming agent, cross-linking agent, and nucleating agent are added to a reaction kettle, and the mass ratio of each component is as follows:

[0010] Methacrylic acid: 40 - 70 parts;

[0011] Methacrylonitrile: 30 - 50 parts;

[0012] Initiator: 1 - 5 parts;

[0013] High-temperature-resistant modifier: 0.1 - 0.5 parts;

[0014] Foaming agent: 1 - 10 parts;

[0015] Cross-linking agent: 1 - 5 parts;

[0016] Nucleating agent: 1 - 5 parts;

[0017] The mixture is uniformly mixed by mechanical stirring to obtain a material mixed solution;

[0018] The obtained material mixed solution is injected into a mold for water bath polymerization reaction; after the reaction is completed, heating and foaming are carried out to obtain a high-toughness, high-strength and high-temperature-resistant PMI foam material.

[0019] Furthermore, the temperature of the water bath polymerization reaction is 25 - 120 °C, and the time is 100 - 350 minutes.

[0020] Furthermore, the heating and foaming temperature is 140 - 250 °C, and the foaming time is 0.5 - 10 hours.

[0021] Furthermore, when the material mixed solution is injected into the mold, the filling rate inside the mold is 40% - 80%.

[0022] Furthermore, the initiator is selected from at least one of benzoyl peroxide, diisopropylbenzene peroxide, di-tert-butyl peroxide, and azobisisobutyronitrile.

[0023] Further, the blowing agent is selected from at least one of nitrogen, carbon dioxide, n-pentane, and isopentane.

[0024] Further, the crosslinking agent is selected from at least one of divinylbenzene, trimethylolpropane triacrylate, bisphenol A diglycidyl ether, and m-xylylene diacrylate.

[0025] Further, the nucleating agent is selected from at least one of silica nanoparticles, alumina nanoparticles, boron nitride nanoparticles, and titanium dioxide nanoparticles.

[0026] Further, the high-temperature resistant modifier is a styrene containing benzocyclobutene group, and its preparation method is as follows:

[0027] To 200 - 300 parts of toluene, 13 - 26 parts of 4-vinylbenzocyclobutene (CAS: 99717-87-0), 0.05 - 0.7 part of bis-(2-methylallyl)cycloocta-1,5-diene ruthenium (CAS: 12289-94-0), 25 - 50 parts of 4,4′-dimercapto stilbene (CAS: 614756-39-7), and 2 - 6 parts of sodium ethoxide are slowly added, and the mixture is stirred at 65 - 75 °C for 40 - 100 min, and then toluene is distilled off to obtain the high-temperature resistant modifier.

[0028] Reaction mechanism of the high-temperature resistant modifier:

[0029] The 4-vinylbenzocyclobutene undergoes a thiol-vinyl addition reaction with one thiol group of 4,4′-dimercapto stilbene; bis-(2-methylallyl)cycloocta-1,5-diene ruthenium undergoes a thiol-vinyl addition reaction with one thiol group of 4,4′-dimercapto stilbene; to obtain a stilbene containing benzocyclobutene and cycloocta-1,5-diene ruthenium, which can participate in the polymerization reactions of methacrylic acid and methacrylonitrile, improving the high-temperature resistance of the PMI foam.

[0030] Beneficial effects of the high-temperature resistant modifier:

[0031] Benzocyclobutene and cycloocta-1,5-diene ruthenium as specific functional groups, their introduction into the PMI foam may change the molecular structure of the material in the following ways, thereby enhancing the thermal stability of the material: The introduction of benzocyclobutene and cycloocta-1,5-diene ruthenium may increase the π-π interactions between molecules, and these interaction forces contribute to stabilizing the molecular structure, reducing the movement and rearrangement of molecular chains at high temperatures, thereby improving the thermal stability of the material.

[0032] The introduction of benzocyclobutene and ruthenium cycloocta-1,5-diene increases the glass transition temperature of the PMI foam, enabling the material to maintain a solid structure at higher temperatures and making it less prone to deformation or flow. Benzocyclobutene and ruthenium cycloocta-1,5-diene may reduce the thermal decomposition rate of the material at high temperatures by increasing the rigidity and stability of the molecular chains. This means that the PMI foam can maintain its structure and properties for a longer time in a high-temperature environment.

[0033] Technical effects:

[0034] 1. High-temperature stability: The PMI foam material prepared by the present invention still has good mechanical strength and toughness under high-temperature conditions and is suitable for long-term high-temperature environments.

[0035] 2. Excellent strength and toughness: The material exhibits high tensile strength and toughness, can withstand complex and variable external forces, and is suitable for application scenarios with high strength requirements such as aerospace.

[0036] 3. Low density: The foam material has a low density, which helps to reduce the structural weight and is suitable for lightweight and high-strength structural requirements.

[0037] 4. Good formability: The material has good forming properties and is easy to process into complex shapes to meet various structural design requirements. Detailed implementation manners

[0038] The following describes the detailed implementation manners of the present invention in detail. It should be understood that the specific implementation manners described herein are only used to illustrate and explain the present invention and are not used to limit the present invention.

[0039] Testing methods:

[0040] The apparent density is determined in accordance with "GB / T 6343-2009 Plastics and rubbers - Determination of apparent density";

[0041] The tensile properties are determined in accordance with "ASTM-D638-2010 Plastics - Tensile";

[0042] The compression properties are determined in accordance with "GB / T 8813-2008 Rigid cellular plastics - Determination of compression properties";

[0043] The heat distortion temperature is determined in accordance with "DIN 53424 High-temperature dimensional stability under flexural stress and compressive stress".

[0044] Example 1

[0045] A high-toughness, high-strength and high-temperature-resistant PMI foam, characterized by comprising the following steps:

[0046] Methacrylic acid, methacrylonitrile, initiator, high-temperature resistant modifier, foaming agent, crosslinking agent, and nucleating agent are added to a reaction kettle, and the mass ratio of each component is as follows:

[0047] Methacrylic acid: 40 g;

[0048] Methacrylonitrile: 30 g;

[0049] Initiator: 1 g;

[0050] High-temperature resistant modifier: 0.1 g;

[0051] Foaming agent: 1 g;

[0052] Crosslinking agent: 1 g;

[0053] Nucleating agent: 1 g;

[0054] The mixture is uniformly mixed by mechanical stirring to obtain a material mixture;

[0055] The obtained material mixture is injected into a mold for water bath polymerization reaction; after the reaction is completed, heating and foaming are carried out to obtain a high-toughness, high-strength, and high-temperature resistant PMI foam material.

[0056] The temperature of the water bath polymerization reaction is 25 °C, and the time is 350 minutes.

[0057] The heating and foaming temperature is 140 °C, and the foaming time is 10 hours.

[0058] When the material mixture is injected into the mold, the filling rate inside the mold is 40%.

[0059] The initiator is selected from benzoyl peroxide.

[0060] The foaming agent is selected from nitrogen.

[0061] The crosslinking agent is selected from divinylbenzene.

[0062] The nucleating agent is selected from silica nanoparticles.

[0063] The high-temperature resistant modifier is benzocyclobutenylstilbene, and its preparation method is as follows:

[0064] 13 g of 4-vinylbenzocyclobutene (CAS: 99717-87-0), 0.05 g of bis-(2-methylallyl)cycloocta-1,5-diene ruthenium (CAS: 12289-94-0), 25 g of 4,4′-dithiostilbene (CAS: 614756-39-7), and 2 g of sodium ethoxide are slowly added to 200 g of toluene, and the mixture is stirred at 65 °C for 100 min. Then, toluene is distilled off to obtain the high-temperature resistant modifier.

[0065] Example 2

[0066] A high-toughness, high-strength and high-temperature-resistant PMI foam, characterized by comprising the following steps:

[0067] Add methacrylic acid, methacrylonitrile, initiator, high-temperature-resistant modifier, foaming agent, crosslinking agent, and nucleating agent into a reaction kettle, and the mass ratio of each component is:

[0068] Methacrylic acid: 50 g;

[0069] Methacrylonitrile: 45 g;

[0070] Initiator: 2.5 g;

[0071] High-temperature-resistant modifier: 0.2 g;

[0072] Foaming agent: 3.5 g;

[0073] Crosslinking agent: 2.5 g;

[0074] Nucleating agent: 2 g;

[0075] Mix the mixture evenly by mechanical stirring to obtain a material mixture;

[0076] Inject the obtained material mixture into a mold and carry out a water bath polymerization reaction; after the reaction is completed, carry out heating and foaming to obtain a high-toughness, high-strength and high-temperature-resistant PMI foam material.

[0077] The temperature of the water bath polymerization reaction is 60 °C and the time is 250 minutes.

[0078] The heating and foaming temperature is 200 °C and the foaming time is 7.5 hours.

[0079] When the material mixture is injected into the mold, the filling rate inside the mold is 60%.

[0080] The initiator is selected from dicumyl peroxide.

[0081] The foaming agent is selected from carbon dioxide.

[0082] The crosslinking agent is selected from trimethylolpropane triacrylate.

[0083] The nucleating agent is selected from alumina nanoparticles.

[0084] The high-temperature-resistant modifier is benzocyclobutenyl stilbene, and its preparation method is:

[0085] Slowly add 17 g of 4-vinylbenzocyclobutene (CAS: 99717-87-0), 0.25 g of bis-(2-methylallyl)cycloocta-1,5-diene ruthenium (CAS: 12289-94-0), 35 g of 4,4′-dimercaptostilbene (CAS: 614756-39-7), and 4 g of sodium ethoxide to 250 g of toluene. Mix and stir at 70 °C for 60 min, then distill off the toluene to obtain a high-temperature resistant modifier.

[0086] Example 3

[0087] A high-toughness, high-strength, and high-temperature resistant PMI foam, characterized by comprising the following steps:

[0088] Add methacrylic acid, methacrylonitrile, initiator, high-temperature resistant modifier, foaming agent, crosslinking agent, and nucleating agent to a reaction kettle, and the mass ratio of each component is:

[0089] Methacrylic acid: 60 g;

[0090] Methacrylonitrile: 45 g;

[0091] Initiator: 4 g;

[0092] High-temperature resistant modifier: 0.35 g;

[0093] Foaming agent: 8 g;

[0094] Crosslinking agent: 4 g;

[0095] Nucleating agent: 4 g;

[0096] Mix the mixture evenly by mechanical stirring to obtain a material mixture.

[0097] Inject the obtained material mixture into a mold for water bath polymerization reaction; after the reaction, carry out heating and foaming to obtain a high-toughness, high-strength, and high-temperature resistant PMI foam material.

[0098] The temperature of the water bath polymerization reaction is 90 °C and the time is 160 minutes.

[0099] The heating and foaming temperature is 235 °C and the foaming time is 3 hours.

[0100] When the material mixture is injected into the mold, the filling rate inside the mold is 60%.

[0101] The initiator is selected from di-tert-butyl peroxide.

[0102] The foaming agent is selected from isopentane.

[0103] The crosslinking agent is selected from bisphenol A diglycidyl ether.

[0104] The nucleating agent is selected from boron nitride nanoparticles.

[0105] The high-temperature resistant modifier is styrene containing benzocyclobutene group, and its preparation method is as follows:

[0106] Slowly add 22 g of 4-vinylbenzocyclobutene (CAS: 99717-87-0), 0.5 g of bis-(2-methylallyl) cycloocta-1,5-diene ruthenium (CAS: 12289-94-0), 45 g of 4,4′-dimercaptostilbene (CAS: 614756-39-7), and 5 g of sodium ethoxide into 250 g of toluene, and mix and stir at 70 °C for 80 min. Then distill off the toluene to obtain the high-temperature resistant modifier.

[0107] Example 4

[0108] A high-toughness, high-strength and high-temperature resistant PMI foam, characterized by including the following steps:

[0109] Add methacrylic acid, methacrylonitrile, initiator, high-temperature resistant modifier, foaming agent, crosslinking agent, and nucleating agent into a reaction kettle, and the mass ratio of each component is as follows:

[0110] Methacrylic acid: 70 g;

[0111] Methacrylonitrile: 50 g;

[0112] Initiator: 5 g;

[0113] High-temperature resistant modifier: 0.5 g;

[0114] Foaming agent: 10 g;

[0115] Crosslinking agent: 5 g;

[0116] Nucleating agent: 5 g;

[0117] Mix the mixture evenly by mechanical stirring to obtain a material mixture;

[0118] Inject the obtained material mixture into a mold and carry out a water bath polymerization reaction; after the reaction, carry out heating and foaming to obtain a high-toughness, high-strength and high-temperature resistant PMI foam material.

[0119] The temperature of the water bath polymerization reaction is 120 °C and the time is 100 minutes.

[0120] The temperature of the heating and foaming is 250 °C and the foaming time is 1 hour.

[0121] When the material mixture is injected into the mold, the filling rate inside the mold is 80%.

[0122] The initiator is selected from azobisisobutyronitrile.

[0123] The foaming agent is selected from n-pentane.

[0124] The crosslinking agent is selected from m-phenylenedimethacrylate divinyl ester.

[0125] The nucleating agent is selected from titanium dioxide nanoparticles.

[0126] The high temperature resistant modifier is benzocyclobutenyl stilbene, and its preparation method is as follows:

[0127] 26 g of 4-vinylbenzocyclobutene (CAS: 99717-87-0), 0.7 g of bis-(2-methylallyl)cycloocta-1,5-diene ruthenium (CAS: 12289-94-0), 50 g of 4,4′-dimercaptostilbene (CAS: 614756-39-7), and 6 g of sodium ethoxide were slowly added to 300 g of toluene, and the mixture was stirred at 75 °C for 40 min. Then, toluene was distilled off to obtain the high temperature resistant modifier.

[0128] Comparative Example 1

[0129] The difference from Example 1 is that the high temperature resistant modifier is not used in the preparation process of PMI foam.

[0130] Comparative Example 2

[0131] The difference from Example 1 is that bis-(2-methylallyl)cycloocta-1,5-diene ruthenium is not used in the preparation process of the high temperature resistant modifier.

[0132] Comparative Example 3

[0133] The difference from Example 1 is that 4-vinylbenzocyclobutene is not used in the preparation process of the high temperature resistant modifier.

[0134] Test results:

[0135] Table 1 Mechanical properties of the foam in the examples

[0136]

[0137] Table 2 Mechanical properties of the foam in the comparative examples

[0138]

[0139] It can be seen from the test results of the above examples and comparative examples that the strength, toughness and high temperature resistance of the PMI foam prepared in the examples are better than those of the PMI foam prepared in the comparative examples, which proves the excellent performance of the PMI foam prepared by the present invention.

[0140] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A high-toughness, high-strength and high-temperature resistant PMI foam, characterized in that: The following steps are involved: Methacrylic acid, methacrylonitrile, initiator, high temperature resistant modifier, foaming agent, crosslinking agent and nucleating agent are added into the reaction kettle according to the mass proportions, wherein the mass ratio of each component is: Methacrylic acid: 40-70 parts; Methacrylonitrile: 30-50 parts; Initiator: 1-5 parts; High temperature resistant modifier: 0.1-0.5 parts; Foaming agent: 1-10 parts; Cross-linking agent: 1-5 parts; Nucleating agent: 1-5 parts; The mixture is mixed uniformly by mechanical stirring to obtain a material mixed liquid; The obtained material mixture is injected into a mold to carry out a water bath polymerization reaction; after the reaction is completed, it is heated and foamed to obtain a high-toughness, high-strength and high-temperature resistant PMI foam material; The high temperature resistant modifier is prepared by reacting 4-vinylbenzocyclobutene, bis-(2-methylallyl)cyclooct-1,5-dieneruthenium and 4,4′-dimercaptostilbene; The high temperature resistant modifier is benzocyclobutene-containing diphenylethylene, and its preparation method is as follows: Slowly add 13-26 parts of 4-vinylbenzocyclobutene, 0.05-0.7 parts of bis-(2-methylallyl)cyclooct-1,5-dieneruthenium, 25-50 parts of 4,4'-dimercaptostilbene, and 2-6 parts of sodium ethoxide into 200-300 parts of toluene, mix and stir at 65-75°C for 40-100 minutes, and remove toluene by distillation to obtain a high temperature resistant modifier.

2. The high-toughness, high-strength, high-temperature-resistant PMI foam according to claim 1, characterized in that: The water bath polymerization reaction temperature is 25-120° C. and the reaction time is 100-350 minutes.

3. The high-toughness, high-strength, high-temperature-resistant PMI foam according to claim 1, characterized in that: The heating and foaming temperature is 140-250° C., and the foaming time is 0.5-10 hours.

4. The high-toughness, high-strength, high-temperature-resistant PMI foam according to claim 1, characterized in that: When the material mixture is injected into the mold, the filling rate inside the mold is 40%-80%.

5. The high-toughness, high-strength, high-temperature-resistant PMI foam according to claim 1, characterized in that: The initiator is selected from at least one of benzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide and azobisisobutyronitrile.

6. The high-toughness, high-strength, high-temperature-resistant PMI foam according to claim 1, characterized in that: The foaming agent is selected from at least one of nitrogen, carbon dioxide, n-pentane and isopentane.

7. The high-toughness, high-strength, high-temperature-resistant PMI foam according to claim 1, characterized in that: The crosslinking agent is selected from at least one of divinylbenzene, trimethylolpropane triacrylate, bisphenol A diglycidyl ether, and isophthalic acid dienyl ester.

8. The high-toughness, high-strength, high-temperature-resistant PMI foam according to claim 1, characterized in that: The nucleating agent is selected from at least one of silicon dioxide nanoparticles, aluminum oxide nanoparticles, boron nitride nanoparticles, and titanium dioxide nanoparticles.

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